Structures and electronic properties of defects on the borders of silicon bonded wafers

The complex research of the structure and electronic properties of defects occurring on the bonding border of twist misfit Si(001) wafers of n-type conductivity was carried out by the methods of transmission electron microscopy, deep level transient spectroscopy (DLTS), and photoluminescence. The revealed defects main are two types of dislocation structure: the orthogonal dislocation network composed of two screw dislocation families and zigzag mixed dislocations. The dislocation structures observed are the sources of intense luminescence, whose spectrum differ considerably from the standard dislocation luminescence spectrum at all investigated misfit angles of bonded Si wafers. It is shown that an increase of the misfit angle results in a strong transformation of the dislocation luminescence spectra consisting in the changes of the spectra form and a decrease in the integral luminescence intensity. In the studied samples, by means of the deep level transient spectroscopy method, the presence of deep centers whose concentration increases with an increase of the misfit angle of the bonded wafers is revealed. It is established that the deep centers are related to the dislocation structures observed by means of transmission electron microscopy.